Means and method for on-line determination of the aromatic, naphthene and paraffin contents of charge oil

ABSTRACT

Where Delta T1 and Delta T2 are the temperature drops across the first and second reactors, FA is the aromatic content of the charge oil in percent volume, M is the average molecular weight of the charge oil, T is the weighted average reactor inlet temperature in *F, P is the inlet pressure of the first reactor in psig, H is the hydrogen to hydrocarbon mole ratio and RSV is the reciprocal liquid hourly space velocity. Signals are provided, corresponding to different sensed operating conditions and properties of the charge oil during the reforming operation, to analog computers. The analog computers provide signals in accordance with Equations 1 and 2 which are used to develop outputs corresponding to the aromatic, naphthene and paraffin contents of the charge oil. Outputs corresponding to the naphthene and the paraffin volume percent contents of charge oil being reformed by a catalytic reforming unit, along with an output corresponding to the aromatic volume percent content, are provided during the reforming operation in accordance with the following equations:

United States Patent White 1 May 30, 1972 [54] MEANS NIETHOD FOR ON-LINE the reforming operation in accordance with the following DETERMINATION OF THE AROMATIC, equamns NAPHTHENE AND PARAFFIN, 1 lAT +2.94(H8)+0.l04602(P-550) CONTENTS OF H E 01 +0.141123(M-117.5)+0.002308(T930)' I +0.o36a41 n-s)('r930)| Assasvss I [72] Inventor: William D. White, Nederland, Tex.

' +0.0115268(P550)(ii8)+0.000602621(P550)(T-930) [73] Assignee: Texaco Inc., New York, NY. XN 7 2(R -M (H- )l +62 54 0.5470904+0.0088876 01(T930 ):0.0 0163' 22(P5'5 0) [22] Filed: Dec. 30, 1970 2 lAT,+0.0775I601(P-550)+1.85(li8)+0.383795(M-117.5)

+l3.4276(RSV0.476)+0.005342901(T930)*+0.06190l(T-930) [21] Appl. No.:- 102,732 +0.27s49'7(Rsv-0.47e ('r930)+0.o05999501 T-930 M 117.5

KN l44.29602+0.0009998862(P-550)(T930)+0.2464407(ll8)| I 0.8316077+0.008959372(T930)0.0024203(P550) [52] U.S. Cl. .,.....235/l51.l2, 208/64, 208/D1G. l (3') Naphthene c0ntent=0.5(XN,+XN,)

5i lnt.'Cl. ..Cl 35 04 G06 7 58 and E58} 2 (4) Paraifin content=l00FA-naphthene content I Where AT and AT- 'are the temperature drops across the first [56] d i cued and second reactors, FA is the aromatic content of the charge UNITED STATES PATENTS .oil in percent volume, M is the average molecular weight of the charge oil, Tis the weighted average reactor inlet temperature in F, P is the inlet pressure of the first reactor in psig, H is 3,497,449 2/1970 Urban ..235/l51.l2X

Primary ExaminerEugene G. Botz AttorneyThomas H. Whaley and Carl G. Reis 57 ABSTRACT Outputs corresponding to the naphthene and the paraffin volume percent contents of charge oil being reformed by a catalytic reforming unit, along with an output corresponding to the aromatic volume percent content, are provided during the hydrogen to hydrocarbon mole ratio and RSV is the reciprocal liquid hourly space velocity. Signals are provided, corresponding'to difierent sensed operating conditions and properties of the charge oil during the reforming operation, to analog computers. The analog computers provide signals in accordance with Equations l and 2 which are used to develop outputs corresponding to the aromatic, naphthene and paraffin contents of the charge oil.

Patented May 30, 1972 3 Sheets-Sheet l Patented May 30, 1972 s Sheets-Sheet 2 QN w.

w a. a. a. S R

Patented May 30, 1912 s sheets-sneet :5

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to petroleum refineries and, more particularly, to a system and method for use with a catalytic reforming unit.

2. Description of the Prior Art A magazine article entitled Computer Control of Catalytic Reforming Processes, by Reuben Silver, appeared in the Mar. 28, 1960 issue of Oil and Gas Journal. In the article, Mr. Silver lists process variables for catalytic reforming; however, he does not state how these process variables may be used to determine'the aromatic, naphthene and paraffin contents of the charge oil. Nor is it obvious to one skilled in the art how the aromatic, naphthene and paraffin contents may be determined on-line, during the catalytic reforming operation, based on the aforementioned magazine article.

SUMMARY OF THE INVENTION An output is provided corresponding to the concentration of an ingredient in charge oil being reformed in a catalytic reforming unit. The catalytic reforming unit includes two or more reactors and recycles a portion of the gas product during the reforming process. Sensors sense the temperatures of the oil in the reactors. A pressure sensor senses the pressure in at least one reactor and provides a corresponding signal. The charge oil and the recycle gas are sampled while sensors provide signals corresponding to the flow rates of the charge oil and the recycle gas. A circuit provides signals corresponding to the average molecular weight M of the of the charge oil and the hydrogen to hydrocarbon mole ratio H in accordance with the charge oil and the recycle gas samples and the charge oil and recycle gas flow rate signals. A chromatograph samples the charge oil and provides a signal corresponding to the aromatic content FA of the charge oil. A network connected to the temperature and pressure sensors and to the previously mentioned circuit provides the output corresponding to the content of an ingredient in the charge oil, in accordance with the temperature signals, the pressure signal, the aromatic content FA signal, the average molecular weight M signal and the 7 hydrogen to hydrocarbon mole ratio H signal.

One object of the present invention is to determine the naphthene content of the charge oil with an on-line system during catalytic reforming.

Another object of the present invention is to determine the aromatic content of the charge oil with an on-line system during catalytic reforming.

Another object of the present invention is to determine the paraffin content of the charge oil with an on-line system during catalytic reforming.

Another object of the present invention is to provide an online system for determining the naphthene and-paraflin contents of the charge oil during catalytic reforming in accordance with sensed temperatures of the reactors in a catalytic reforming unit, a sensed pressure in a reactor, the aromatic content, the average molecular weight of the charge oil and the hydrogen to hydrocarbon mole ratio.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein one embodiment of the invention is illustrated by way of example. It is to be ex pressly understood, however, that the drawings are for illustration purposes only and are not to be construed as defining the limits of the invention.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial block diagram and a partial schematic diagram of a catalytic reforming unit with a system constructed in accordance with the present invention, for providing outputs corresponding to the naphthene and parafiin contents of charge oil being reformed by the catalytic reforming unit.

FIGS. 2 and 3 are detailed block diagrams of analog computers shown in FIG. 1.

DESCRIPTION OF THE INVENTION During catalytic reforming, a portion of the naphthenes in the charge oil is converted to aromatics The aromatic content of the reformed oil determines the quality of thereforrned oil and is directly related to the naphthene content of the charge oil. The system of the present invention provides for on-line measuring of the aromatic, naphthene and paraffin contents of the charge oil so that the control of the catalytic reforming process may be improved.

Referring to FIG. 1, there is shown a catalytic reforming unit in which change oil in a line 3 enters a heater 6. The charge oil is heated to a predetennined temperature and supplied through line 9 to a fixed bed catalytic reactor 8-where a reaction occurs. The effluent leaves reactor 8 by way of a line 10. During the catalytic reaction, there is a temperature drop so that the efiluent in line 10 must be heated again before charging to the-next reactor. The effluent from reactor 8 is subjected to three more stages of catalytic reaction by reactors 8A, 8B and 8C; with heating prior to each stage provided by heaters 6A, 6B and 6C; before being applied to a product separator 11. Elements identified by a number witha sufiix are connected and operate in a similar manner as elements having the same number without a suffix. Product separator 11 provides product oil in a line 12 and gas in a line 14. A portion of the gas is recycled by a conventional compressor 15 through a line 16. The recycle gas enters line 3 and is used to retard the deterioration of the catalyst in reactors 8 through 8C.

The operation of a catalytic reforming unit of the type shown in FIG. 1 is explained in greater detail in U.S. Application Ser. No. 806,766, new U.S. Pat. No. 3,563,883, filed Dec. 30, 1968 by Westby et a]., of which the present inventor is a joint inventor, and assigned to Texaco Inc. assignee of the present invention.

A conventional flow rate sensor 20 senses the flow rate of charge oil in line 3 and provides a corresponding signal to signal means 21 which is also continuously sampling the charge oil and the recycle gas in lines 3 and 16, respectively. Signal means 21 receives a signal corresponding to the flow rate of the recycle gas in line 16 from a conventional flow rate sensor 22. Signal means 21 embodies the elements and concepts of U.S. Ser. No. application 97,571 filed Dec. 14, 1970 by W. L. Hopkins et aL, of which the present inventor is a joint inventor, and assigned to Texaco Inc. assignee of the present invention. In the description of the last mentioned U.S. application, signals E,, E and the output from amplifier 112 correspond to the average molecular weight M of the charge oil, to the flow rate of the charge oil and to the hydrogen to hydrocarbon mole ratio H respectively, and are signals E,, E and E respectively, in the description of the present invention.

Chromatograph means 23 samples the charge oil in line 3 and provides a signal I5, corresponding to the aromatic content FA of the charge oil. Chromatograph means 23 includes a chromatograph which may be of the type manufactured by Beckman Instruments with a Beckman Model 620 programmer and a Beckman Model D analyzer.

As previously mentioned, there occurs a temperature drop each reactor during the reaction. It has been noted from empirical data that the temperature drop across the first two reactors substantially effect the determination of the naphthene and parafiin contents of the charge oil while the final two reactors have little eflect on the determination. Temperature sensors 25 through 25C, which may be thermocouples, sense the inlet temperatures to reactors 8 through 8C, respectively, and provide corresponding signals E through E respectively. Sensors 25D and 25B sense the outlet temperatures of reactors 8 and 8A, respectively, by sensing the temperature of the effluent leaving those reactors and provide signals E and B respectively, corresponding to the sensed outlet temperatures. Signals E,, E, are applied to subtracting means 26 which subtracts signal l'i from signal E to provide a signal 5,, corresponding to the temperatures drop at AT across reactor 8. Similarly, signal E is subtracted from E by subtracting means 26A to provide a signal E, corresponding to the temperature drop AT, across reactor 8A.

A weighted average inlet temperature T signal E is developed by weighting each inlet temperature according to the percentage of the overall catalyst in the corresponding reactor. lnlet temperatures signals Ii, through E are supplied to multipliers 28 through 28C, respectively, where they are multiplied with direct current voltages V through V respectively, corresponding to the weighting factors for the reactors to provide signals E through E respectively. Summing means 32 sums signals E through E to provide the Tsignal E For example, when reactor 8 through 8C have 20, 20, 20 and 40 percent, respectively, of the catalyst in the catalytic reforming unit, voltages V through V correspond to 0.2, 0.2, 0.2 and 0.4, respectively. Let the inlet temperatures of reactors 8 through 8C be 940, 930, 920 and 950 F Signals through 15C would then correspond to 188, 186, 184 and 380 F and signal E would correspond to 938 RA conventional pressure transducer 36 senses the inlet pressure P of reactor 8 and provides a corresponding signal E An analog computer 37, which will hereinafter be described in detail, uses signals E E E E,, E E and E along with received direct current voltages V; through V to provide a signal E, in accordance with equation 1 of the abstract.

Thefollowing table relates direct current voltages to corresponding terms or coefficients in Equation 1:

Similarly, an analog computer 38, which will also be hereinafter described in detail, uses signals 5,, E E E E E and E along with received direct current voltages V V,,, V,, V V V through V and V through V to provide a signal E in accordance with Equation 2 of the abstract.

The'following table relates the received direct current voltages to the terms or coefi'ncients in Equation 2.

Term

Voltage Term or coefficient Voltage or coefficient v. s v,, 13.4276

V;- 550 V 0.005342901 V; t 17.5 V, 0.061907 v,., 930 v, 0.278497 V 0.476 V, 0.005999501 V 62.5 V, 44.29602 V 2 V, 0.0009998862 V, Known volume of catalyst V 0.2464407 V, 0.07751601 V, 0.8316077 V 1.85 V 0.008959372 V, 0.383795 V, 0.0024203 The naphthene content is determined by using the XN,

age V corresponding to 0.5 to provide a signal E which corresponds to the naphthene content of .the charge oil.

The sum of the paraflin content and the naphthene content and the aromatic content of the charge oil constitutes a whole. Therefore, the paraffin content can be determined by subtracting the naphthene and aromatic contents from 100 which,

is done by subtracting means 44. Subtracting means 44 subtracts signals 5, E from a direct current voltage E which corresponds to 100, to provide a signal E corresponding to the paratfin content of the charge oil.

Referring to Flg. 2, there is shown a detailed blockdiagram of analog computer 37. Subtracting means 45, 45A, 45B and 45C subtract voltages V V V, and V respectively, from signals E E,, E and E respectively, to provide signals corresponding to the terms (T-930), (ll-8), (P-550) and (M- 1 17.5), respectively, in Equation 1. A multiplier 46 effectively squares the signal from subtracting means 45 to provide a sigrnal corresponding to (7 930). The signal from multiplier 46 is multiplied with voltage V, by a multiplier 47 to provide a signal corresponding to 0.0023208 (7 930). A multiplier 50. multiplies the signal from subtracting means 45A with voltage V; to provide a signal corresponding 2.94(H-8) The signals from subtracting means 45, 45A are multiplied together by a multiplier 53 to apply a signal to another multiplier 54. Multiplier 54 multiplies the signal from multiplier 53 with voltage V to provide a signal corresponding to 0036641 (T-930) (H-8). n

Multipliers 57, 58 multiply the signals from subtracting means 458 and 45C with voltages V, and V respectively, to provide signals corresponding to 0.l04662(P-550) and 0.l41123(M -l17.5), respectively. Summing means 60 sums the signals from multipliers 47, 50, 54, 57 and 58 and the AT, signal E Voltage V is multiplied with the signal from subtracting means 45 by a multiplier 62 to provide a signal corresponding to 0.55 10265( T-930). The output from subtracting means 45A is efl'ectively squared by a multiplier 63 and the square signal multiplied with voltage V by another multiplier 64 to provide a signal corresponding to 0.l537442(H-8). A multiplier 68 multiplies the outputs from subtracting means 45A, 45B together and the resulting signal is multiplied with voltage V by a multiplier 69 to provide a signal corresponding to 0.01 l5268(P-550) (H-8). Multipliers 70, 71 are arranged in a similar manner as multipliers 68 and 69, respectively, to multiply the outputs from subtracting means 45, 45B and voltage V, to provide a signal corresponding to 0.000602621 (T-930) )P-550).

A divider 75 divides the voltage V by charge oil flow rate signal E, to provide a signal corresponding to the reciprocal space velocity RSV to subtracting means 45!). Subtracting means 45D subtracts voltage V from the RSVsignal from divider 75 to provide a signal corresponding to (RSV-0.476). The output from subtracting means 45D is multiplied with voltage V by a multiplier 76 to provide a signal corresponding to 8.664779(RSV-0.476). A multiplier 77 multiplies the outputs from subtracting means 45A, 45D together and the resulting signal is multiplied with voltage V by a multiplier 78 to provide a signalcorresponding to 2.529762 (RSV- Summing means 80 sums the signals from multipliers 62, 64, 69, 71, 76, and 78 and voltage V,. Subtracting means 81 subtracts a sum signal from summing means 80 from a sum signal from summing means 60 to provide a signal corresponding to' the numerator of the fraction in Equation 1.

The outputs from subtracting means 45, 45B are multiplied with voltages V and V respectively, by multipliers 83, 84

to provide signals corresponding to 0.008687601(T-930) and 0.00l6322(P-550), respectively. The signal from multiplier- 83 is summedwith voltage V by summing means 87 to provide a sum signal. The signal from multiplier 84 is subtracted from the sum signal from summing means 87 by subtracting means 88 to provide a signal corresponding to the denominator of the fraction in Equation 1. A divider 90 divides the numerator signal from subtracting means 81 by the denominator signal from subtracting means 88. The resulting signal is applied to summing means 91 where it is summed with voltage V A multiplier 93 multiplies voltage V and the EA signal E, together and the resulting signal which corresponds to 2FA, is subtracted from the signal provided by summing means 94 by subtracting means 92 to provide the XN signal E Referring to FIG. 3, analog computer 38 includes subtracting means 100 through 100C which subtract voltages V V V and V from signals E,,,, E E and E respectively, to provide signals corresponding to (P-550), (M-l 17.5), (T-930) and (H-8), respectively. Multipliers 101 through 101C multiply the signals from subtracting means 100 through 100C, respectively, with voltages V V V and V respectively, to provide signals corresponding to 0.0775l60l(P-550), 0.383795(M-l 17.5), 0.06l907(T-930) and l.85(H-*), respectively.

A multiplier 104 multiplies the signals from subtracting means 100, 1008 together and the resulting signal is multiplied with voltage V by a multiplier 105 to provide a signal corresponding to 0.0009998862(P-550) (T-930). Similarly, multipliers 104A and 105A multiply the signals from subtracting means 100A, 1008 and voltage V to provide a signal corresponding to 0.00599950l(T-930) M-M-l 17.5). Multipliers 1048, 1053 cooperate in a similar manner to provide a signal corresponding to 0.278497(RSV-0.476) T-930) in' accordance with the signals from subtracting means 100B, 100D and voltage V Subtracting means 100D provides the (RSV- 0.476) signal by subtracting voltage V,. from the output from a divider 106 which divides the voltage V by the charge oil flow rate signal E Multipliers 110, 110A effectively square the signals from subtracting means 1008 and 100C, respectively, and the resulting signals are multiplied with voltages V and V by multipliers 1 l l and 1 1 1A, respectively, to provide signals corresponding to 0.005342901(T-930) and 0.24644O7(H-8) respectively. The signal from subtracting means 100D is multiplied with voltage V by a multiplier 115 to provide a signal corresponding to l3.4276(RSV-0.476).

Summing means 120 sums the AT signal E with the signals from multipliers 101, 101A, 101B, 101C, 105A, 105B, 111 and 115; while summing means 121 sums the signals from multipliers 105, 111A and voltage V Subtracting means 130 subtracts the signal 'from summing means 121 from the signal from summing means 120 to provide a signal corresponding to the numerator of the fraction in Equation 2.

The signal from subtracting means 100B is multiplied with voltage V by a multiplier 133 to provide a signal corresponding to 0.008959372( T-930) which is summed with voltage V, by summing means 135. The signal from subtracting means 100 is multiplied with voltage V by a multiplier 136 to provide a signal corresponding to 0.0024203(P-550). Subtracting means 137 subtracts the signal from multiplier 136 from the sum signal from summing means 135 to provide a signal corresponding to the denominator of the fraction in Equation 2.

A divider 140 divides the numerator signal from subtracting means 130 by the denominator signal from subtracting means 137. A multiplier 141 multiplies voltage V and the FA signal E together; the resulting signal, which corresponds to 2FA, is subtracted from the signal from divider 140 by subtracting means 144. Summing means 146 sums the signal from subtracting means 144 which voltage V to provide the XN signal E There may be a slight constant error between the measured naphthene content, using Equations 1 and 2, and the actual naphthene content for 'a particular catalytic reforming unit. When known, the error can be compensated for by adding to or subtracting from the numerators of the fractions in Equations 1, 2. This may be accomplished by applying a direct current voltage to summing means 60 or 80, depending on the nature of the correction, to aflect the numerator of the fraction in Equation 1 accordingly. Similarly, another direct current voltage may also be applied to summing means 120 or 121 to compensate for the error.

It would be obvious to one having ordinary skill in the art to use a digital computer to determine the naphthene, paraffin, and aromatic contents of the Charge oil. All that would be necessary would be to convert signals E E E 15,, 12,, and 15,, through E 15. and E to digital signals, using conventional analog-to-digital converters, and to program the digital computer to solve the equations in the abstract.

The device of the present invention as heretofore described determines the aromatic, naphthene and paraffin contents of charge oil during the reforming of the charge oil by a catalytic reforming unit. The determination is made in accordance with sensed temperatures of reactors in the catalytic reforming unit, a sensed pressure in a reactor, the average molecular weight of the charge oil and the hydrogen to hydrocarbon mole ratio.

What is claimed is:

1. A system for providing an output corresponding to a content of an ingredient of charge oil being reformed by a catalytic reforming unit having a plurality of reactors and recycling a portion of the gas product, comprising chromatograph means for sampling the charge oil and providing a signal corresponding to the aromatic content FA of the charge oil, means for providing signals corresponding to sensed temperatures of the reactors, means for sensing the pressure P in at least one reactor and providing a signal corresponding thereto, means for sensing the flow rates of the charge oiland the recycle gas and providing corresponding signals, means connected to the flow rate signal means and sampling the charge oil and the recycle gas for providing signals corresponding to the average molecular weight M of the charge oil and the hydrogen to hydrocarbon mole ratio H in accordance with flow rate signals and the samples, and means connected to the chromatograph means, to the temperature signal means, to the pressure sensing means and to the molecular weight-mole ratio signal means for providing the output corresponding to the content of an ingredient in the charge oil, in accordance with the temperature signals, the pressure signal, the average molecular weight M signal and the hydrogen to hydrocarbon mole ratio H signal.

2. A system as described in claim 1 in which the output corresponds to the naphthene content of the charge oil.

3. A system as described in Claim 2 further comprising means connected to the chromatograph means and .to the output means for providing another output corresponding to the paraffin content of the charge oil in accordance with the arcmatic content signal, the naphthene content output and the following equation:

Parafiin content -aromatic content-naphthene content 4. A system as described in claim 2 in which the temperature signal means provides a signal for each sensed inlet temperature of the reactors and-a signal for each sensed outlet temperature of the first two reactors, and the sensed pressure is the sensed pressure in the first reactor.

5. A system as described in claim 4 in which the output means includes a circuit receiving the inlet temperature signals and direct voltages, each direct current voltage corresponding to a percent of the catalytic reforming units catalyst present in a different reactor, and providing a signal corresponding to the average weighted temperature T of all the inlet temperatures and subtracting means connected to the temperature signed means, one subtracting means receiving the inlet and outlet temperature signals for the first reactor and providing a signal corresponding to the temperature drop AT across the first reactor, the other subtracting means receiving the inlet and outlet temperature signals and providing a signal corresponding to the temperature drop AT across the second reactor.

+0.036641(H8) T-930) {85.83793 0.5510265(T 930) +8.664779( RSV 0.476)

9. A method as described in claim 8 further comprising determining the paraffin content of the charge oil in accordance with the aromatic content FA and the naphthene content of the charge oil and the following equation:

paraffin content 100 aromatic content naphthene content.

10. A method as described in claim 8 in which the sensed temperatures are the inlet temperatures of the reactors and the outlet temperatures of the firsttwo reactors, and the sensed pressure is the sensed pressure in the first reactor.

, '+0.01'15268(P5 50) (H-8) +0.000602621(P550) (T-930) {AT2+0.07751601(P-55O) 1.85(l 8) +0.3s379s M 117.5 13.4276( RSV-0.476 +0.005342901(T930)2+0.061907( T930) +0.27s497 RSV 0.476) "r-930 0.005999501(T930)(M117.5)}

XN {44.29602-I- 0.0009998862(P550) (T-930) +0.2464407(ll 8)*} s i Output corresponding to t en 99E9 5? 9r2pfi zlm where RSV is reciprocal space velocity which is the volume the catalyst divided by the flow rate of the charge oil.

7. A method for determining an ingredient of charge oil being reformed by a catalytic reforming unit having reactors and recycling a portion of the gas product, sensing temperatures of the reactors, sensing the pressure of at least one reactor, sensing the flow rate of the charge oil, sensingthe flow rate of the recycle gas, sampling the chargeoil, sampling the recycle gas, determining the average molecular weight M of the charge'oil in accordance with the sensed flow rate of the charge oil and the charge oil sample, determining the hydrogen to hydrocarbon mole ratio H in accordance with the sensed flow rates of the charge oil and the recycle gas and with the samples of the'charge oil andthe recycle gas, determining the aromatic content FA of the charge oil in accordance with the charge oil sample and determining the ingredient content of the charge oil in accordance with the sensed temperatures,

of 30 11. A method as described in claim 10 in which the determining of the naphthene content step includes determining the aromatic content FA of the charge oil, determining the temperature drops AT and AT, across the first and second reactors, respectively, from the inlet and outlet temperatures of the first and second reactors, weighting the inlet temperature of each reactor in accordance with the percent of the catalytic reforming unit catalyst contained in the reactor, and summing the weighted temperatures to obtain, the average weighted temperature T.

1 A method as described in claim 11 in which the naphthene content is determined in accordance with the temperature drops AT and AT,, the sensed charge oil flowrate, the hydrogen to hydrocarbon mole ratio H, the average molecular weight M of the charge oil, average weighted inlet temperature T, and the pressure P and the following equations:

N 2.529762( RSV-0.476) (H-8) +0.1537442(H 8) {AT +0.07751601(PO) 1.85(H8) +0.383795(M 117.5) I +13.4276(RSV 0.476) 0.005342901(T 930) 0.061907( T- 930) 0.278497( RSV- 0.476.) T 930) 0.005999501(T930) (M- 117.5)

X {44.29602-l- 0. 0009998862(P 550) (T- 930) 0.2464407(H 8)*] I 0.8316077+0.008959372(T930)0.0024203(P550) and the naphthene QMPEiiQiXNiiPN L the sensed pressure, the aromatic content FA the average molecular weight M and the hydrogen to hydrocarbon mole ratio H. v t e s. A method as described in claim 7 in which the ingredient content of the charge oil to be determined is the naphthene content.

where RSV is the reciprocal space velocity which'is deter- A mined by dividing the known volume of the catalyst in the catalytic reforming unit by the flow rat of the charge oil.

2273 3 UNITED STATES PATENT OFFICE 4 CERTIFICATE OF CORRECTIDN Patent: No. 3, ,93 Dated MAY 3 97 Inventqr WILLIAM D 0 WHITE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

5- "AT" at Column 3, line 9 should read AT "supplied" at Column 3, line 13 should read --applied-- at Column 1, line 14 should read --E )P-55O)" at Column 4, line 53 should read --(P-550)-- "EA" at Column 5, line 8 should read --FA-- "l.85(H-*)" at Column 5, line 21 should read -l.85(H-8)'"' "M-M-ll7.5" at Column 5, line 29 should read --(M-ll7.5)-- "signed" at Column 6, line 69 should read signal-- "direct signal current" at Column 7, line 8 should read "direct current signal-- "XN" at Column 7, line 51 should read "m Signed and sealed this 9th day of January 1973.

(SEAL) Attest':

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting; Officer Commissioner of Patents 

2. A system as described in claim 1 in which the output corresponds to the naphthene content of the charge oil.
 3. A system as described in Claim 2 further comprising means connected to the chromatograph means and to the output means for providing another output corresponding to the paraffin content of the charge oil in accordaNce with the aromatic content signal, the naphthene content output and the following equation: Paraffin content 100-aromatic content-naphthene content
 4. A system as described in claim 2 in which the temperature signal means provides a signal for each sensed inlet temperature of the reactors and a signal for each sensed outlet temperature of the first two reactors, and the sensed pressure is the sensed pressure in the first reactor.
 5. A system as described in claim 4 in which the output means includes a circuit receiving the inlet temperature signals and direct voltages, each direct current voltage corresponding to a percent of the catalytic reforming units catalyst present in a different reactor, and providing a signal corresponding to the average weighted temperature T of all the inlet temperatures and subtracting means connected to the temperature signed means, one subtracting means receiving the inlet and outlet temperature signals for the first reactor and providing a signal corresponding to the temperature drop Delta T1 across the first reactor, the other subtracting means receiving the inlet and outlet temperature signals and providing a signal corresponding to the temperature drop T2 across the second reactor.
 6. A system as described in claim 5 in which the output means includes computer means connected to the circuit, to the subtracting means, to the chromatograph means, to the pressure sensing means and to the molecular weight-mole ratio means for providing the output in accordance with the T signal, the Delta T1 and Delta T2 signals, the FA signal, the P signal, the charge oil flow rate signal and the H signal, a received direct signal current voltage corresponding to the volume of the catalyst in the catalytic reforming unit and the following equations:
 7. A method for determining an ingredient of charge oil being reformed by a catalytic reforming unit having reactors and recycling a portion of the gas product, sensing temperatures of the reactors, sensing the pressure of at least one reactor, sensing the flow rate of the charge oil, sensing the flow rate of the recycle gas, sampling the charge oil, sampling the recycle gas, determining the average molecular weight M of the charge oil in accordance with the sensed flow rate of the charge oil and the charge oil sample, determining the hydrogen to hydrocarbon mole ratio H in accordance with the sensed flow rates of the charge oil and the recycle gas and with the samples of the charge oil and the recycle gas, determining the aromatic content FA of the charge oil in accordance with the charge oil sample and determining the ingredient content of the charge oil in accordance with the sensed temperatures, the sensed pressure, the aromatic content FA the average molecular weight M and the hydrogen to hydrocarbon mole ratio H.
 8. A method as described in claim 7 in which the ingredient content of the charge oil to be determined is the naphthene content.
 9. A method as described in claim 8 further comprising determining the paraffin content of the charge oil in accordance with the aromatic content FA and the naphthene content of the charge oil and the following equation: paraffin content 100 -aromatic content - naphthene content.
 10. A method as described in claim 8 in which the sensed temperatures are the inlet temperatures of the reactors and the outlet temperatures of the first two reactors, and the sensed pressure is the sensed pressure in the first reactor.
 11. A method as described in claim 10 in which the determining of the naphthene content step includes determining the aromatic content FA of the charge oil, determining the temperature drops Delta T1 and Delta T2 Across the first and second reactors, respectively, from the inlet and outlet temperatures of the first and second reactors, weighting the inlet temperature of each reactor in accordance with the percent of the catalytic reforming unit catalyst contained in the reactor, and summing the weighted temperatures to obtain, the average weighted temperature T.
 12. A method as described in claim 11 in which the naphthene content is determined in accordance with the temperature drops Delta T1 and Delta T2, the sensed charge oil flow rate, the hydrogen to hydrocarbon mole ratio H, the average molecular weight M of the charge oil, average weighted inlet temperature T, and the pressure P and the following equations: 